Houston-based private equity firm EnerVest has posted a spectacular loss in one of its energy funds, a troubling sign that other firms could yet face a reckoning after a three-year oil price downturn.

EnerVest’s $2 billion energy fund that borrowed heavily to buy up oil and gas wells when crude prices were soaring has essentially gone bust, The Wall Street Journal reported. The blowup is expected to leave the pensions, endowments and charitable foundations that invested in the fund with just pennies on the dollar at best, according to the newspaper.

The fund’s lenders, which are led by Wells Fargo, are seeking to take control of the assets, people familiar with the situation told the Journal.

“We are not proud of the result,” John Walker, EnerVest’s co-founder and chief executive, said in a statement to the Journal.

The scale of the loss is highly unusual for a private equity firm of EnerVest’s size. Just a handful of private equity outfits worth at least $1 billion have lost money for investors, and even then, losses of 25 percent or more are virtually unprecedented, the Journal reported, citing analysis by investment firm Cambridge Associates and public pension records.

The Journal traced the failure to EnerVest’s strategy of taking out debt to amplify returns in the fund, which began investing in oil and gas wells in 2013 and focused on improving their output. As oil prices plunged from more than $100 a barrel in 2014 to a low of $26 a barrel last year, the value of the wells, which served as collateral on the debt, eroded. That triggered repayment demands from lenders that EnerVest could not meet.

While more than 100 drillers have filed for bankruptcy, credit and equity markets, as well as private equity, have remained available to many producers, giving them a lifeline and helping to avoid the type of contagion once feared by investors.

Private equity firms are typically able to keep their money in investments for several years, allowing them to ride out storms like the prolonged oil price downturn. Still, The Wall Street Journal notes that EnerVest’s competitors also turned to borrowing to amplify returns from their investments in oil and gas wells. That raises fresh concerns that more funds could fail.